Method of making cyanamid



F. S. WASHBURN. METHOD OPJMAKING GYA-NAMID. APPLICATION FILED FEB. 23 l 1910.

Patented Sept. 26, 1911.

2 SHEETS-SHEET 1.

r fw M ,M

@mi ['1 wsse;

F. S. WASHBURN.

METHOD 0F MAKING GYANAMID. APPLICATION FILED 11:15.23, `1910.

1,004,509. 1 Patented Sept. 26, 1911.

2 SHEETS-SHEET 2.

QS N m m1: o

, 'UNITED sTATEs PATENT onirica.A

FRANK S. WASHIBURN, OF NASHVILLE, TENNESSEE, ASSIGN'OR TO AMERICAN CYAN- AMID COMPANY, F BALTIMORE, MARYLAND, A'COBPORATION OF MAIN-E.

Specification of Letters Patent.

Application filed February 23, 1910. Serial No. 545,52?.

To all whom it may concern:

f Be it known that I, FRANK S. VAsnBURiQ, a citizen of the United States,res1dmg at Nashville, in the county of Davidson and State of Tennessee, have invented certain new and useful Improvements in MethodsY of Making Calcium ACyanamid; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which-it appertains to make and use the same.

This invent-ion relates to a process of and an apparatus for treating calcium carbidto form calcium cyanamid and has for its object to shorten the process and to improve the apparatus now in' use for this purposelVith these and other objects in view the invention consists inthe novel combinations of steps, details of construction and combif nations of parts more fully hereinafter disclosed and particularly pointed out in the claims.

., Referring to the accompanying drawings forming a part of this specification in which like numerals refer to like parts. in all Ythe viewsz-Figure 1, is a diagrammatic,

sectional, elevational view of an apparatus suitable for carrying out my invention Fig. 2, is a sectional view taken on the line 2-2 of Fig. 1; Fig. 3, is a sectional .view of a modied portion of the apparatus shown in Fig. l; and,-Fig. 4, is a diagrammatic, ele vational, sectional view of a still further modifiedy form of vthe inventiom4 Calcium cyana-mid has heretofore ether/ been madevdirectly from the molten carbid, 0r, in externally heated retorts, or, in internally heated ovemwherein-has been placed pulverized carbid and' brought into contact with nitrogen at a proper temperature.

The operations 1n the retorts and ovens have been conducted with charges of con' venient weight, the operation being interv Amittent and involving a changerof manipu-A lations, periods 'of inactivity, anexcessive amount of expenslve apparatus, and delays .and undesirable variations intemperature.

The most serious disadvantage, however, inthe present methods Aof manufacture is the, Ien th of time required to complete the re action betweenthe nitrogen gas and the. powdered carbid necessary to th'e formation of calcium cyanamid. The present invention obviates all ofi these diticulties, and 'a in Fig. e.

suitable -apparatus for practicing the same consists of a revolving kiln or retort 1, snit- .ably mounted as upon rollers 2 and 3 with its longitudinal axis slightly inclined, and driven conveniently frm'a source of .power 4, through the gears 5 and 6, the latter in- 'termeshing with the circular rack 7, as illustrated.

Into the upper end of the retort.. 1, the powdered carbid is fed as by the screw conveyer fronnnunicating with'the passage 9 connected with the branch pipes v10 and 11 controlled byithe valves 12 and 13, and leading to the reservoirs 14 and 15 vprovided "with the top valves 16 and 17. The conveyer 8 may be operated by any v'suitable source of power, as 1.8, and the carbid is delivered" into the retort in a tine stream Where -it settles on the bottom of thesame .and is immediately caughtup by roughnesses or depressions onl the inside of the-retort or by the vanes or fingers 20 as they revolve, and thereupon continuously dropped to the bot tom again in streams 21, as best illustrated The retort being inclined, the carbid ,21

Patented Sept. 26.17.1911. t

will find its way to the lower, end .of .the

same in a period of time depending upon the inclination of the retort and the speed at which it is driven, after having been raised and dropped a nulnber'oi times die-V pendingupon the number of blades 20. In other words, it is evident that the carbid can be made to stay in the retort as long or as short a time as may be desired, and that it may be stirred by the blades 2011s much' as may be found necessary.

Nitrogen gas 4is preferably admitted through the pipe 25 entering the stationary `plug 26 surrounded by the stuffing box 27,

and since the powdered carbid is thoroughly stirred, as above described, the said nitro-V gen isbrought into the most intimate con tact with' every. particle of the carbid. The nitrogen .is prevented from escaping froml the apparatus at the upper end by means of the valves 16 and 17. v'When rbid bcing fed from one of the' containers, as 14,

its valve 12 may 'beg opened While its valve 16 is closed. .In the meantime the `valve 13A of the containers 15 may be closed and the@ valve 1-7 o ned, whereupon' the containe.

15 may be lled 4Without stopping the apparatus. Ofcourse, after the container 14 is exhausted its valve 12 may be closed and its through the passage 30 making a tight joint as at 31 with the annular bearing 32 and communication with the conveye'r 33 driven from the source of power 34 and communicating with the pipes Bend 37 entering respectively the delivery reservoirs 38 and 39 .4 and controlled, respectively, by the valves 40 'and 41. The delivery reservoirs 38 and 39 are respectively provided at their lower ends with Valves 42 and43.. lt is evident that the valves 40, 41, 42 and 43 may be manipulated'inthe manner above described to i enable the operator to receive y'cyanamid into one reservoir While emptying from the y other, and vice Versa andv that the nitrogen may be prevented from escaping during the operation.

The inner cylinder 45 is preferably made of suitable rev resisting material'such for example as porcelain or re clay, and it is separated from the outer cylinder 1 by a` space 46-wl1ich will soon become filledr with nitrogen. The cylinder 45 may be heated in any suitable manner to start the reaction between the nitrogen and the carbid and .l have shown an electric resistance 47 through which current is passed from the leads 48V and 49 contacting respectively with the rings 50y and 51 encircling the outer cylinder 1.-

But, it is evident, that any other suitable means of heating may be substituted for the resistanceshow j v Y As is well known, in order to start the reaction between the nitrogen and the carbid it is necessary to raisev it to an initial "tem- 4peraftuure of about 12009,@.-when the reaction starts. The react-ion between the nitrogen and the .powdered carbid is so highly exothermic that it will maintain the necessary temperature tor a continuous reaction, either without the continued use of the independent heating lappliance or with some aid therefrom.` The powdered carbid and 'the nitrogen at the proper temperature 'produce cyanamidwhich together with certain-waste products, chiedy freecarbid. and lime, may be delivered from the lower end of lthe -retort, :as above stated. it is also well lnuown.

that an eliicient process for producing cyanamid must keep the temperature in the retort fleet-Ween certain limits, and that since.

the reaction going on in the old style retorts was variable the temperature therein likewise varied. In order to render my process automatic in this respect, l provide a suitable thermostatic device, diagrammatically shown"as at' 60, whichv enters the retort,

closes a `circuit when the temperature gets a. suitable dei too high and thereby through rice 61 operates a relay to cut oli' the source 4ot'current in a manner well known. lt is also Well known' that if the pressure in the lretort gets too high or too low very serious disadvantages l likewise provide any suitf' able pressure device diagrammatically I'shown as at 65 which communicates with the interior of the retort, and Whenthe pressure gets too high or too lonr suitable circuits are opened or closed and the pump orother de vice which delivers nitrogen is correspondingly controlled. 'l`lfil1crx1iostatic devices which I have found suitablcor my purposes being well known in the art, and 'their specific constructions forming no` part, of vmy inventionthey are not further illustrated herein.

In Fig. 3 the 'parts 'are the same as in Fig. -1 except a resistance rod l0 preferably provided with a porcelain brother refractory cover 71 is employed instead of the resistance conductor 47. y y

lin the diagrammatic. view/0f a Jfurther modification shownin Fig. 4 theretort is stationary, the carbid enters at i 5 falls puesta series of battle plates Z6 in' relatively nne streams, the nitrogen entersat'hand the retort may be 'heated by the resistance 47 or by any other suitable means. f lt will be obvious in all the formaftnat my process by causing the-nitrogen to be thoroughly mixedwith every particle of the car- 'bid .insures a rapid and speedy conversion of the carbid into cyauamid, and thereby very greatly reduces the time now necessary to yaccomplish this conversion and at the sameV time greatly-'increases the output of the factory. ln addition to this,- since the passage of the carbid throughthe retort is absolutely under the control of the operator and since the temperature-in the' retort as well as the pressure of the nitrogen can either be observed at all times or can be automatically regulated, itlwill be seenthat the 'cyanainid product is exceedingly uniform.

it is obvious' that those skilled in the art may vary the details of construction and the @arrangement of parts without departing from the spirit 'of this invention, and, thereore, I do not wish to be limited to Suchresvtures, except as may be required by the claims.'

1. The process of making calcium cyanamid from calcium carbid which consists in causing the finely divided carbid to be repeatedlyraised and dropped while moving through an atmosphere of nitrogen; and in maintaining seidnitrcgcn and carbid at the requisite temperature to produce the cyanamid, substantially as described. -f l 2. The process o-making calcium cyanisp www

amid from calcium carbid which consists in causin the finely divided carbid to rise and fall w ile' Vmoving through and becoming intimately mixed with an atmosphere of nitrogen; in raising said carbid and nitrogen' to the temperature necessary to start the reaction; and in maintaining a temperature thereafter suitable for keeping up the reaction, substantially as describe 3. The process=of making calcium cyan-V amid from calcium carbid, which consists in causing the finely divided carbid to progressively move through and become mtimatel)I mixed with an atmosphere of nitro# gen; 1n raising said carbid and nitrogen to the temperature necessary to start the reaction; and in automatically maintaining a temperature and ressure in said atmosphere thereafter suitab e for keeping up the reaction, substantially as described.

4. The process of making-calcium cyanamid from finely dividedcalcium carbid which consists in causing said carbid to rise and fall while moving through an/ atmosphere of nitrogen; in maintaining the `same at the requisite temperature to produce cyanamid; and in so regulating the speed at which said carbid moves as tcccause subA stantiallyall of it to react with thc nitrogen, substantially as described.

'5. The process of making calcium -cyanamid from calcium carbid, which consists in repeatedly subjecting in the presence of nitrogen small quantities of said carbid to the action of a heated'surfacc; and in raising said surface to a temperature sufficient to form said calcium cyanaxnid, substantiaily as described. A

In testimony whereof, I affix my signature, in presence of two witnesses.

, FRANK S. VVASHBURN.

Witnesses STANLEY HANNA, CHAS. BRIGGMAN. 

